The effect of interfacial mass transfer of slip-rising gas bubbles on two-phase flow in the vertical wellbore/pipeline

During drilling or oil recovery, it is common that the formation trap gas invades the vertical wellbore/pipeline to cause the gas-liquid two-phase flow, which brings challenges and dangers to wellbore/pipeline pressure control. In this paper, coupling the interfacial mass transfer theory of slip-rising bubbles based on bubble hydraulics to the gas-liquid two-phase flow theory, a new transient non-isothermal gas-liquid two-phase flow model in the vertical wellbore/pipeline was developed. In this model, the effects of flow regime and heat transfer on the mass transfer rate were considered. The proposed model was validated using the measured experiment data and field data. Using this model, the effect of interfacial mass transfer of slip-rising bubbles on the evolution of gas-liquid two-phase flow in a special gas kick scenario was analyzed. The simulation results indicated that the mass transfer rate between oil dispersion and invasion gas was relatively slow, which made the gas not instantaneously dissolved in the oil dispersion or not instantly saturated the oil dispersion. Under the same gas invasion rate, the fraction and mass of free gas calculated by this model were always larger than those obtained by Yin's model, resulting in a faster of the bottomhole pressure reduction rate and pit gain increase rate. Additionally, increasing the gas concentration and flow rate could promote the interphase mass transfer rate, while increasing the temperature would inhibit it. This model could characterize the wellbore/pipeline gas-liquid two-phase flow with interphase mass transfer in more detail and accurately. (C) 2020 Elsevier Ltd. All rights reserved.